Cyclic topology is a common motif in natural product structures.1 A subset of natural products, cyclic peptides, display a wide variety of biological activities, and unique conformational properties due to their circular architecture.2-6 In 2010, a multicomponent peptide macrocyclization reaction mediated by aziridine aldehydes was reported. These amphoteric species incorporate a nucleophilic amino group and electrophilic aldehyde.2-8 The final macrolactamization step, which involved a transannular attack by the exocyclic NH aziridine on a mixed anhydride intermediate, furnished a N-acyl aziridine containing macrocycle with an exocyclic amide bond. The non-canonical exocyclic amide moiety was later found to modulate a well defined intramolecular hydrogen bonding network.9 The success of this multicomponent macrocyclization reaction relies upon on the reversible dimerization of the aziridine-aldehyde monomer, which allowed both aziridine and aldehyde functional groups to maintain independent reactivity.10 
However, improved macrocyclization processes are desirable.